Zen is a decent chap in a tricky system. "He never makes the right political decision," Sewell said.

In the opener, one boss tells him the suspect must be found guilty; a higher-up secretly tells him thesame suspect must be found innocent. Then - on a wholly different matter - there's an ex-con who wantsto kill Zen ... and an office beauty (played by Caterina Murino) who wants to love him.

It was a tough role, he said, modified by the fact that he was working in a gorgeous place. "Just to ...walk back through Rome at the end of the evening was one of the great pleasures."

The two men have one important person in common. That's Tom Stoppard, Ed's father, an acclaimedwriter who has won Tonys for four of his plays and an Oscar for "Shakespeare in Love."

Sewell has been in many of those plays. "Rufus has been (my father's) surrogate son for about the last20 years," Ed Stoppard quipped. "I'm working through a lot of issues, actually."

Indeed, he says it was seeing Sewell in his father's "Arcadia" that made him realize he wanted to be anactor. His mother - Miriam Stoppard, a physician, author and member of the Order of the British Empire- was not happy about this; his father had mixed feelings.

"He'd spent most of his adult life auditioning very, very good actors (who gave) very, very goodauditions and watching them walk out of the room without the job," Ed Stoppard said.

Now his son has joined that overcrowded field - and is getting hired. This season, he's been in all three"Masterpiece" strands - Contemporary ("Any Human Heart"), Classic (starring in "Upstairs, Downstairs") and now "Mystery," as one of the creeps who makes Zen seem noble by comparison.